Analysis of nine zone diagram for voltage control of substation considering the load characteristics

Nine zone diagram is commonly used to keep voltage stability and reactive voltage balance by changing reactive power compensation equipment or the transformer tap in the substation. In this paper, the principles of voltage and reactive power control based on nine zone diagram are reviewed, and then the control effect of reactive power compensation and transformer tap with different types of load model is analyzed. In the end, the effect of six different types of load on voltage control is simulated, and the results show that: the change trend of voltage or reactive power is roughly the same when changing reactive power compensation; the change trend of the voltage is roughly the same, but the change trend of reactive power has great difference when changing transformer tap.